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參數(shù)資料
| 型號： | UC3844TD |
| 廠商： | 意法半導(dǎo)體 |
| 英文描述： | HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER |
| 中文描述： | 高性能電流模式PWM控制器 |
| 文件頁數(shù)： | 1/15頁 |
| 文件大?。?/td> | 228K |
| 代理商： | UC3844TD |
UC3842T UC3843T
UC3844T UC3845T
September 2001
HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER
.
TRIMMED OSCILLATOR FOR PRECISE FRE-
QUENCY CONTROL
.
OSCILLATOR FREQUENCY GUARANTEED
AT 250kHz
.
CURRENT MODE OPERATION TO 500kHz
.
AUTOMATIC FEED FORWARD COMPENSA-
TION
.
LATCHING PWM FOR CYCLE-BY-CYCLE
CURRENT LIMITING
.
INTERNALLY TRIMMED REFERENCE WITH
UNDERVOLTAGE LOCKOUT
.
HIGH CURRENT TOTEM POLE OUTPUT
.
UNDERVOLTAGE LOCKOUT WITH HYSTER-
ESIS
.
LOW START-UP AND OPERATING CURRENT
DESCRIPTION
The UC384XT family of control ICs provides the
necessary features to implement off-line or DC to
DC fixed frequency current mode control schemes
with a minimal external parts count. Internally imple-
mented circuits include a trimmed oscillator for pre-
cise DUTY CYCLE CONTROL under voltage lock-
out featuring start-up current less than 0.5mA, a pre-
cision reference trimmed for accuracy at the error
amp input, logic to insure latched operation, a PWM
comparator which also provides current limit control,
and a totem pole output stage designed to source
or sink high peak current. The output stage, suitable
for driving N-Channel MOSFETs, is low in the off-
state.
Differences between members of this family are the
under-voltage lockout thresholds and maximum duty
cycle ranges. The UC3842T and UC3844T have
UVLO thresholds of 16V (on) and 10V (off), ideally
suited to off-line applications The corresponding
thresholds for the UC3843T and UC3845T are 8.5 V
and 7.9 V. The UC3842T and UC3843T can operate
to duty cycles approaching 100%. A range of zero to
< 50 % is obtained by the UC3844T and UC3845T by
the addition of an internal toggle flip flop which blanks
the output off every other clock cycle.
BLOCK DIAGRAM
(toggle flip flop used only in UC3844T and UC3845T)
UVLO
S/R
5V
REF
34V
INTERNAL
BIAS
VREF GOOD
LOGIC
2.50V
T
S
R
OSC
R
1V
CURRENT
SENSE
COMPARATOR
2R
+
-
PWM
LATCH
7
5
4
2
1
3
8
6
ERROR AMP.
Vi
GROUND
RT/CT
VFB
COMP
CURRENT
SENSE
VREF
5V 50mA
OUTPUT
D95IN331
Minidip
SO8
1/15
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| UC3844TN | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
| UC3844W | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:SMPS Controller |
| UC3844Y | 制造商:TI 制造商全稱:Texas Instruments 功能描述:CURRENT MODE PWM CONTROLLER |
| UC3845 | 制造商:STMicroelectronics 功能描述:3845 |
| UC3845A | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Current Mode PWM Controller |
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